Enzyme binding to its substrate is very important to carry out a chemical reaction. Substrate binds at the active site of an enzyme to form an enzyme substrate complex and the substrate is transformed into the product.
The specific shape of active site is made by some specific amino acids from the polypeptide chain of amino acids which make globular structure of enzyme. The two regions of active site helps in recognition and binding of substrate (binding site) and then break down of substrate into products (catalytic site).
In literature, mechanism of enzyme action is explained by the help of two models i.e., lock and key model and induced fit model. You can study lock and key model here.
Induced fit model of enzyme action
The lock and key model of enzyme was unable to properly explain the mechanism of enzyme action. In 1958, Koshland proposed induced fit model to clarify enzyme action on the basis of new evidences. This model explains the changes in conformational or shape during the binding process.
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Diagram explaining induced fit model of enzyme action. |
Key points of induced fit model
The main points of induced fit model are:
- This model suggests that an enzyme optimizes or changes the shape of active site as it connects with its substrate to form the final enzyme-substrate complex structure.
- According to this model, enzyme is not a rigid structure but it is flexible and induces changes at the active site to fit with the substrate. This allows enzyme to bind a variety of related substrate.
- The changes in shape helps enzyme to perform its catalytic function more efficiently.
However, one shortcoming of this model is that it does not explain chemical changes that will occur during enzyme catalyzed reaction.
Video Lesson
References
- Csermely, P., Palotai, R., & Nussinov, R. (2010). Induced fit, conformational selection and independent dynamic segments: an extended view of binding events. Nature Precedings, 1-1.
- Koshland Jr, D. E. (1995). The key–lock theory and the induced fit theory. Angewandte Chemie International Edition in English, 33(23‐24), 2375-2378.
- Image created in BioRender.com
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